Hard disk drives are common information storage devices. FIG. 1a provides an illustration of a typical disk drive unit 100 essentially consisting of a series of rotatable disks 101 mounted on a spindle motor 102, and a Head Stack Assembly (HSA) 130 which is rotatable about an actuator arm axis 105 for accessing data tracks on disks during seeking. The HSA 130 includes at least one drive arm 104 and a head gimbal assembly (HGA) 150. Typically, a spindling voice-coil motor (VCM) is provided for controlling the motion of the drive arm 104.
Referring to FIG. 1b, the HGA 150 includes a slider having a thermally assisted head 110, and a suspension 190 to load or suspend the slider 103 thereon. The suspension 190 includes a load beam 106, a base plate 108, a hinge 107 and a flexure 109, all of which are assembled together. When the disk drive is on, a spindle motor 102 will rotate the disk 101 at a high speed, and the slider 103 will fly above the disk 101 due to the air pressure drawn by the rotated disk 101. The slider 103 moves across the surface of the disk 101 in the radius direction under the control of the VCM. With a different track, the slider 103 can read data from or write data to the disk 101.
Referring to FIG. 1c, the slider 103 includes a substrate 1031 having an air bearing surface (ABS) 1032 processed so as to provide an appropriate flying height and the thermally assisted head 110 for reading and writing. The thermally assisted magnetic head 110 includes a write element (not labeled) and a read element (not labeled). This thermally assisted head 110 applies a thermal energy source 111, such as a laser diode at or near the location of the write element. Conventionally, the thermal energy source 111 is bonded to the substrate 1031 by using a solder, for example. This thermal energy source 111 provides energy to a portion of the magnetic recording medium, which reduces the medium's coercivity. After that, writing is performed by applying write magnetic field to the heated portion; therefore the writing operation is facilitated. Generally proposed is a method in which the magnetic recording medium is irradiated and heated with near-field light. The spot of the near-field light is set to be minute; the very small spot size can be realized which is free of diffraction limit. Meanwhile, a waveguide is provided for propagating the laser light to the ABS 1032 by a surface of a plasmon generator (PG), thereby providing near-field light, instead of directly applying the laser light to an element that generate near-field light. Commonly, the PG is made of materials having high light absorption and low light refraction index. Such a plasmon generator and a waveguide are disclosed, for example, in US Patent Publication No. 2010/0103553 A1 and U.S. Pat. No. 8,059,496 B1.
U.S. Pat. No. 8,059,496 B1 discloses a write element having a main pole 11, a PG layer 12, and a waveguide 17, as shown in FIG. 1d. The PG layer 12 is recessed from the ABS 10-10. There is a magnetic layer 11e that is effectively an extension of the main pole 11 formed between the PG layer 12 and the ABS 10-10, and the magnetic layer 11e is comprised of the same material as in the main pole 11. Namely the magnetic layer 11e is a part of the main pole 11. When a laser is emitted to the write element, the laser is guided to the PG layer 12 by the waveguide 17. As known, the main pole 11 and the magnetic layer 11e also have high light absorption characteristic and low light refraction index, thus the near-field light may be reached to the top surface of the magnetic layer 11e to form the near-field light generating surface 121, finally propagated to the ABS 10-10. By this token, the near-field light generating surface 121 and the ABS 10-10 are in the same level as shown in FIG. 1d. 
However, the near-field light generating end of the PG layer 12 and the magnetic layer 11e both of which have high light absorption characteristic and low light refraction index will protrude over the ABS 10-10 as shown in FIG. 1f since high temperature is generated during the writing operation, which may crash the magnetic recording medium surface.
Accordingly, it is desired to provide improved write element, a thermally assisted magnetic head slider, HGA, HDD with the same, and a manufacturing method thereof to overcome the above-mentioned drawbacks.